The difference between electro-galvanizing and hot-dip galvanizing

“Electro galvanized” is just another term for ‘zinc electroplated’. That means the steel is immersed in an aqueous bath, and electricity is used to induce anodes of zinc to dissolve in the aqueous solution, transport the ions, and electroplate them onto the work.

In hot dip galvanizing the work is immersed in molten zinc. As it is withdrawn, the zinc cools and forms a coating of zinc on the work.

Hot dip galvanized coatings are almost always several times thicker and therefore several times as corrosion resistant. There are some other practical differences in the two coatings for different applications as well.

Electroplated zinc coatings can be smooth and shiny, and preferable for aesthetic reasons, whereas galvanizing may be spangled, or gray and drippy. Zinc electroplating is thin and usually does not cause any problems with fasteners, whereas galvanized coatings are heavy and will interfere with fastener threads unless they are specially dimensioned to take the coating into account.

But, as mentioned, galvanized coatings are up to 10x as thick and will always greatly outlast zinc electroplating in any environment. Electroplated zinc coatings are rarely adequate for direct outdoor exposure.

Components with zinc electroplating (electrogalvanizing) will have have a thinner, shinier, drip-free coating, which is usually considered more aesthetically pleasing. Also, hardware that has been zinc plated normally does not have to be cut to special thread dimensions to allow for the coating thickness as is the case with hot-dip galvanized hardware. Plus, the cost of zinc plating should be significantly lower than the cost of hot dip galvanizing.

Zinc plating process whereby the molecules on the positively charged zinc anode attach to the negatively charged sheet steel. The thickness of the zinc coating is readily controlled. By increasing the electric charge or slowing the speed of the steel through the plating area, the coating will thicken.

Tag: Electro galvanized, hot dip galvanizing, wire mesh